Rock drilling apparatus



N. E. WOLFRAM aocx DRILLINGYAPPARATUS Nov. 17, 1959 2 Sheets-Sheet 1filed Nov. 25, 1956 INVENTOR. NORMAN 5:. WQLFRAM ATTORNEYS Nov. 17, 1959N. E. WOLFRAM 2,913,225

ROCK DRILLING APPARATUS Filed Nov. 2a, 1955 2 Sheets-Sheet 2 a? 6/FIC3.5.'

55 I 29, 3a 3a 6 i L 8 5 E 536 3 1- g a 27 INVEN A NORMAN E. WOL AM I 4344 BY Ul! 9 A oRNEYs United States Patent C) 2,913,225 ROCK DRILLINGAPPARATUS NormanE. Wolfram, South Deerfield, Mass. Application November23, 1956, Serial No. 624,128: 4 Claims. (Cl. 255-49 This inventionrelates to drilling rigs and particularly to a rig for wagon drills andthe like for drilling in'rock or other terrain and having a pneumaticdrifter or rotatively and percussively driven hammer drill for actuatinga rock drill bit.

An object of the invention is to provide a drilling device whereby lowpressure air or exhaust air from a pneumatic drifter or pneumatic hammerdrill will be utilized to assist in cleaning the drillings from adrilled hole hehind the bit.

Another object of the invention is to provide structure which willconvey high pressure air through a drifter or drill to the front of abit without appreciable loss in pressure to clean the bit and the holebeing drilled.

Still another object is to provide simple and efficient structure forcontinuously feeding high pressure air without pressure loss to thefront of a bit and exhaust or low pressure air behind the bit during theoperation of the drifter or pneumatic hammer drill for a cooperativecontinuous cleaning action of a drilled hole and the bit.

Further objects, advantages and features will be apparent from thefollowing description and the accompanying drawings.

In the drawings,

Fig. 1 is a front view of a drilling rig constructed and arranged inaccordance with the present invention and as mounted on a conventionalwagon drill mast;

Fig. 2 is a longitudinal sectional view with parts broken away of thedrill rig shown by Fig. 1;

Fig. 3 is an enlarged view of the bit with the lower end of thestructure shown by Figs. 1 and 2 in section and indicating a hole beingdrilled;

Fig. 4 is an enlarged fragmentary view of the front head or chuck end ofthe drifter or hammer drill as shown in Fig. 1 with the drill casing andcoupling shown in section and with the drill shaft removed;

Fig. 5 is a sectional view taken on line 55 of Fig. 2;

and

Fig. 6 is a sectional view taken on line 66 of Fig. 2.

In common types of pneumatic hammer drills or drifters for rock drillinghigh pressure air operates the power tool to deliver the desiredpercussive and rotary action to the drill shaft and bit. High pressureair is also conducted at the same time through a bore in the drill shaftto the face of the bit for blowing drillings from in front of the bitand to clean out the hole behind the bit. In normal deep drillingoperations drillings frequently become piled up in a hole being drilledto the extent that the air pressure being delivered into the bottom partof the hole is insufiicient to remove all drillings by blowing them upand out through the top of the hole. When the operator notices a blockedcondition arising, the drifter can be manipulated to shut off airpressure to the hammer mechanism and to by-pass such air into the boreof the drill shaft. Pressure in the shaft bore is thus supplementedwhile the drilling is interrupted. The increased air blast then liftsthe drillings out of the hole and when clear, the drilling continues asbefore. In diverting air 2,913,225 Patented Nov. 17, 1959 2 pressurewhich normally operates the drifter piston hammer the exhaust line isalso shut off. The exhaust line in such tools normally is open to theatmosphere and it is a feature of the present invention to utilize thepressure of the exhaust line in a manner to assist the cleaning of thehole being drilled and to prevent the need for periodically stopping thedrilling.

raise and lower a pneumatic drifter or rock hammer drill 18 slidablymounted on the mast for manipulating the rig in the usual manner.,

The mechanism of the drifter or rock hammer drill 18 is 'rotatively andpercussively driven by high pressure air from an air inlet conduit 19which is connected with an air compressor (not shown). Drifter 18 has acomposite housing 20 (Fig. 2) with a chuck 21 at its lower end and ahigh pressure air inlet opening 22 at the other end. The hose or conduit19 is connected to the inlet opening 22. i

A piston hammer 23 is slidably mounted in the housing 20 between the twoends'of the housing, a front hammer bearing 24 being provided in thehousing with a distance piece 25 interposed between thehousing innerWall 26 and the bearing 24. A ratchet 27, rifle bar 28, rifle nut 29,chuck driver 30 and chuck driver nut 31 are provided to turn or rotatethe chuck intermittently as the hammer reciprocates. A valve chest 32with an automatic valve 33 feeds high pressure air from inlet opening 22to the piston hammer to reciprocate it in the housing. An exhaust portor opening 34 is also provided in the housing.

The chuck 21 has an inner member 35 and an outer member 36. A drillshaft or drill steel piece in the form of a stub shaft 37 is removablymounted in the chuck. The shaft 37 has a pair of spaced lugs 38 whichseat in longitudinal grooves at 39 in the outer member 36 of the chuck.Outer member 36 has a lower end opening with opposed lug keyways 40(Fig. 5) for initially inserting the lugs 38 in the chuck and forturning into longitudinal grooves 39 after the manner of a bayonetjoint. In other words, grooves 39 are offset from and connected with thekeyways 40. Thus once the lugs have been inserted through the keyways,shaft 37 can be turned to position the lugs for slidable movement in thegrooves 39. Keeper blocks 41 extending to the upper end of member 36 andretained by member 35 (Fig. 5) may also be seated in the longitudinalgrooves 39 to block the keyways 40. The keeper blocks thus provide oneof the guiding surfaces for the lugs 38 and lock them in the grooves 39so that they can slide longitudinally on rebound of the shaft 37 from apiston hammer blow but cannot turn and come out the keyways 40 of thechuck. It may be noted a washer or disc may be held by thecouplingmember 46 (which is attached to the chuck of the housing as willbe later described,

Fig. 4) to support the lower ends of the keepers 41 to maintain themagainst sliding out of the keyways 40. The rotary and percussive actionand principal elements of the drifter assembly are of known constructionand I Couplings 42 provide means for drill shaft extensions to be addedto shaft 37 and a bit 43 is mounted on the drill shaft by an outercoupling, the outer end of the shaft 37 beingthreaded and the drillshaft extensions having threaded ends. Bit 43 has a threaded shaft44 atits rear for connection by the outer coupling 42 to any drill shaftextension.

A drill casing 45 is connected to the housing 20 at its chuck end toencircle shaft 37 and any shaft extensions to a point closely adjacentbit 43. A coupling member 46 with a flange 47 (see Fig. 4) abuts thefront head or chuck end 21 of the housing, the flange having tie rodopenings 48 to receive tie rods 49 extending through the openings. Rods49 are secured at their inner threaded ends to tie rod nuts ,50 whichsecure a conventional pair of casing tie rodsSl to the housing. Nuts 52clamp tie rods 49 to flange 47 and secure the coupling member 46 inposition.

Coupling .46 also has an elbow conduit 53 for low pressure. airconnected as shown by Fig. 1 by a tube 54 to an elbow conduit 55 leadingto the: exhaust port 34 of the housing. The elbow conduit 55 is receivedin the chamber of an exhaust valve housing 55' of the drifter. Thischamber, as will be understood by those skilled in the art, normallycontains a valve for closing off the exhaust when by-passing highpressure air into the bore of the drill shaft. The elbow 55 has aconstantly open port for exhaust as shown at 34' in Fig. 1. Thus exhaustair from the drifter operation will be conducted through the annularspace around the drill shaft 37 and out of the casing 45 behind the bit43. This, as will be seen, is to provide air to supplement high pressureair and assist in cleaning a drilled hole during the drilling. The drillcasing 45 is tightly fitted to the coupling member 46 by a threadedconnection (Fig. 4) with an abutment 56. The casing is concentricallyspaced from the shaft extensions as by a spacer member 57 (Figs. 2 and3) slidably fitting over the drill shaft and having annularly spacedwings or flanges 58 in slidable contact with the interior wall of thedrill casing.

The low pressure exhaust air coming from the casing 45 supplements andcooperates with high pressure air supplied from the high pressure inletopening 22 of the housing 20 through the housing, the drill shaft andbit, and without pressure drop or loss to the front of the bit so as toremove drillings and clear a drilled hole dun'ng drilling. Housing 20has a central axial opening 60 (Fig. 2) at its rear end in which a highpressure air tube spud 61 is mounted. The axial opening is connectedthrough rifle bar 28 and piston hammer 23,

which have like axial openings, all aligned for an air tube 64 to extendfrom the spud through the rifle bar and piston hammer into the chuck.Drill shaft 37 and bit 43' likewise have axial openings 65 and 66 andthe outer end of air tube 64 is slidably fitted in an enlarged axialopening 62 at the inner end of the shaft 37.

A conduit or tube 67 connects the air tube spud 61 with the highpressure inlet opening'22 of the housing. In this manner, high pressureair at the same pressure used in driving the hammer is directedcontinuously and without pressure loss to the front end of the bit.Axial opening 66 of the bit is forked at its front end to direct thehigh pressure air to each side of the tip at the leading face of thebit.

No appreciable loss or drop in pressure occurs between the air tube andthe drill shaft since the air tube 64 extends slidably within the axialopening of the drill shaft and remains in such opening during alloperative phases of the drifter or drill, both when the hammer isdriving the drill shaft and when the drill shaft rebounds.

High pressure air is thus conducted from the inlet opening of thedrifter through to the front of the bit. At the same time, exhaust airwhich otherwise would be vented to the atmosphere and wasted isconducted down into and through the sleeved drill casing 45 to the rearof the bit to assist in cleaning out the drilled hole. Thus material inthe hole blown upwardly from the face of the bit by the high pressureairv is assisted upwardly and out the top of the hole by the exhaust airfrom the casing. Because there is no appreciable pressure loss inconveying the high pressure air to the front of the bit, the exhaust orcasing air delivered behind the bit is always of lower pressure than theair expelled from the bit and cooperates with it rather than workingagainst it in cleaning the bit and clearing the drilled hole. Theholebeing drilled may. thus be kept continuously cleared of drillingsand without interruption of the hammering action.

What is claimed is:

l. Rock drilling apparatus comprising a fluid operated percussive motorhaving an inlet connection with a source of high pressure fluid and anexhaust port, a drill bit mounted to transmit the percussive force ofthe motor tome 'face of a rock, passageway means leading from said inletport to the forward end of said drill bit whereby high pressure fluidwill be directed therefrom and passageway means leading from saidexhaust port to a point adjacent the rear of said drill bit.

2. Rock drilling apparatus as in claim 1 wherein the inlet connection isto a source of pressurized air.

3. Rock drilling apparatus comprising an air driven percussive motorhaving a casing and a reciprocable piston mounted therein, a drill steelmounted in said casingto receive the force of said piston, a drill bitmounted at the outer end of said steel, said percussive motor having anair inlet connected to a source of pressurized air and an exhaust port,said drill bit having passageways opening on its forward end andpassageway means interconnecting the drill bit passageways with said airinlet connection to the source of pressurized air, a tube securedto saidcasing and surrounding said steel in spaced relation, said tubeterminatingjust short of said drill bit to provide an opening thereat,and a passageway means interconnecting said exhaust port and said tubewhereby low pressure air is discharged adjacent the rear of said drillbit;

4. Rock drilling apparatus as in claim 3 wherein said passageway meansconnected with said air inlet comprises a relatively fixed tubecentrally disposed in said piston and received by an opening therein,said drillsteel having a bore slidably and rotatively receiving theouter end of said fixed tube and communicating with said drill bitpassageways and further wherein means are provided for rotating thedrill steel during percussive operation of said motor.

References Cited inthe file of this patent UNITED STATES PATENTS 651,487Leyner June 12, 1900 823,980 Walker June 19, 1906 2,646,967 BuccaneroJuly 28, 1953 FOREIGN PATENTS 328,629 Great Britain Apr. 30, 1930-

